A wide variety of cleaning compositions for hard surfaces have been disclosed in the prior art. Most of these compositions are concerned only with performance, on a wide variety of stains and in a wide variety of conditions. And most hard surfaces are rather resistant to the point that it is generally not a concern that these surfaces may be permanently damaged by the cleaning composition.
However marble and lacquered surfaces are two types of surfaces which do require particular attention, when formulating cleaning compositions for their cleaning. Indeed, marble is mainly composed of calcium carbonate, and is therefore incompatible with cleaning compositions which would be acidic, and/or which would comprise a builder. Indeed, acidity would "dissolve" marble, while the builder, whose function is specifically to bind ions which are present in water and dirt particles, would also bind the calcium in the marble, thereby turning the surface from very shiny to dull, as the introduced surface irregularities lower the reflectance of the surface. We have also found that cleaning products formulated at neutral pH and which contain anionics surfactants also damage marble, probably because the anionic surfactants would also bind the calcium in the marble as described hereinabove. Thus the formulation of an alkaline composition free of anionic surfactants would seem indicated in the present circumstances.
However, the formulation of an alkaline composition does not accommodate the cleaning of lacquered and painted surfaces, such as painted metal surfaces, or lacquered and painted wooden surfaces e.g. lacquered wooden floors. As used herein, lacquers are typically made out of polyurethanes or polyacrylates or mixtures of both, and paint is mainly pigmented polyacrylates, polyvinylacetates or alkydresins. Indeed such surfaces are permanently damaged by alkalinity. Specifically, alkalinity would destroy the lacquer and therefore give the lacquered surface the appearance of dullness or a colour change. Thus it would appear that formulating a cleaning composition which is suitable for cleaning both marble and lacquered surfaces is hindered by incompatible pH requirements.
Also, the absence of an anionic surfactant, which is desirable for preserving the marble, is somewhat incompatible with a good overall cleaning performance, specifically soil solubilization/grease emulsification.
Thus it is an object of the present invention to formulate a liquid composition which is suitable, i.e. safe, for the cleaning of both marble and lacquered surfaces, and which comprises an anionic surfactant so as to provide good cleaning performance, in particular which performs well on grease removal.
In response to this object, we have formulated a liquid composition which comprises at least one anionic surfactant, which is free of strong builders, which is formulated at a mildly acidic to mildly alkaline pH, and which comprises positive divalent ions in amounts so as to saturate the anionic surfactant in the composition.
Indeed, we have found that in the present compositions, the mildly acidic to mildly alkaline pH damages neither marble nor lacquers. Also, the positive divalent ions in a saturating amount for the anionic surfactant prevents the damage on marble, while still allowing the anionic surfactant to perform its cleaning action.
Cleaning composition which are said to be for delicate surfaces are described in EP 511 091, CN 1055198 (title) and CN 10 32 360 (title).